Bottom closure for bag with rectangular cross-section



74 Fig.2

P. KlZlHNLE Filed Aug. 28, 1968 Juiy 7, 1970 BOTTOM CLOSURE FOR BAG WITH RECTANGULAR CROSS-SECTION Inventor.- PAUL KL'JHNLE BY Q Z/M ATTORNEY United States Patent US. Cl. 22958 7 Claims ABSTRACT OF THE DISCLOSURE Bottom closure for a bag of rectangular cross-section in which the closure flaps extending from the narrow wall panels are spaced relative to each other; slits are provided in the broad panel connected flaps to cause portions of these flaps to be followed in response to the folding of the narrow panel flaps; and each of the four flaps are provided with adhesive means for seal tight engagement with each other.

The invention relates generally to a bag and, more particularly, to the bottom closure construction of the bag.

In bags of the type here under consideration, made of paper or similar material, it is important to provide a seal tight closure in order to assure the integrity and effectiveness of the bag. Due to the cross-section of the bag it is at times diflicult to form from a rectangular or square-like blank sleeve a closure construction in which the closing flaps are all in overlapping relationship to assure the seal tight integrity of the bag bottom.

The present invention is concerned with a bottom closure construction in which a seal tight closure is assured even though the cross-sectional area of the bag does not permit an overlapping relationship between the flaps extending from the narrow side walls, so that the terminating edges of these inwardly folded, and oppositely arranged, flaps are spaced, more or less, relative to each other thus establishing a void therebetween.

In bags of the type herein under consideration the blank is folded to provide a rectangular cross-section thereby establishing alternating broad and narrow wall panels each thereof being provided at one end thereof with a closure flap. The flaps extending from the broad panels are each provided with two spaced incisions or slits, which extend parallel to the longitudinal fold line between the broad and narrow panels and in close transverse proximity thereto. The end of each slit is spaced from the rear edge of the respective flaps, located adjacent to each panel, whereby the slit does not extend throughout each flap so that during the inward folding of the narrow panel flaps certain outer parts of the broad panel flaps are simultaneously folded therewith and are brought into an engagement position with the bottom side of adjacent broad panel closure flaps.

In bags of this type the bottom closure is usually completely seal tight when the cross-section of the bag is such that the opposing narrow panel flaps may be formed to extend in overlapping or at least abutting relationship.

In order to establish a secure and seal tight bottom closure, in the absence of such overlapping or abutting relationship between the flaps of the narrow wall panel, the bag in accordance with this invention is provided with opposing narrow panel flaps in which each, on the top surface thereof, is secured with a strip of adhesive material. These strips may either terminate at the side edges of the flaps or may extend for a predetermined distance beyond these edges and upon the inner surface of the flaps which are hingedly connected to the broad panels.

The novel construction in accordance with this invention provides a bag having a bottom closure which establishes seal tight integrity even in those cases in which the disadvantageous cross-sectional area has heretofore not permitted a degree of seal tightness usually required for bags.

In another embodiment of this invention, the bag blank is grooved along its fold lines in a manner which heretofore has been used only in the fabrication of carton packages. The grooving of the fold lines make it possible that the fold flaps can be turned exactly at the place provided therefor which is not only important for the integrity of the closure, which is, of course of considerable importance, but also contributes to the clean look of the bag exterior.

It is therefore the primary object of this invention to provide an improved bottom closure construction for bags which facilitates a greater degree of seal integrity.

It is a further and more specific object of this invention to provide a bottom closure construction for bags in which seal tight integrity is obtained despite the spaced relationship between the flaps hingedly connected to the narrow panels of a bag having a rectangular cross-section.

It is a still further object of this invention to provide a bag in which the blank of which the bag is formed is grooved along its fold lines to facilitate the proper positioning of the closure flaps in order to improve the seal. This approach having the added advantage of improving the appearance of the bag.

For a better understanding of the present invention, together with other and furthe objects thereof, reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the drawing:

FIG. 1 is a perspective view of a partly constructed bag bottom closure which is secured to a forming mandrel; and

FIG. 2 is a bag blank for a bag having a bottom construction as shown in FIG. 1.

Referring now to FIGS. 1 and 2, the bottom portion of the bag is formed from a blank 1 which inculdes, in order to establish a rectangular cross-section, two relatively broad wall panels 2, 3 and two comparatively narrow wall panels, 4, 5 with the narrow panels alternating between the broad panels as clearly shown in FIG. 2. Adjacent to the broad panel 2 there is provided a longitudinally extending seam flap which is adapted to be adhe sively fastened to the opposite end of the bag sleeve, i.e. narow panel 5, which during the formation of the bag is placed into overlapping relationship with the seam 6.

From each of the panels 2, 3 and 4, 5 there extends, longitudinally, one closure flap 11, 12 and 13, 14 respectively, for forming the bottom of the bag. These flaps are hingedly connected to their respective panel by means of fold lines 7 to 10. In the preferred embodiment, the fold lines are grooved by means of conventionally known tools.

Each of the flaps 11 and 12, i.e. those hingedly connected to the broad panels 2 and 3 of the bag, are provided with an incision or slit. Slits 21 and 22 being cut into panel flap 11 and slits 23 and 24 having been cut into flap 12. These slits extend from the terminal edge 20 of the blank 1 toward the Wall panels, parallel to the fold lines 7 to 10. The slits are spaced relative to each other and each thereof is arranged adjacent to a fold line identified in the drawing by numerals 7 to 10. The longitudinal incisions which establish the aforementioned slits do not extend all the way through said flaps but terminate at a location substantially spaced from the wall panels, more particularly, from the transversely extending fold line 15 which delimits the area between the panels and the flaps. As a result of this construction, the closure flaps 11 and 12, which are positioned between the incisions 21, 22 and 23, 24, are narrower than the total width of the broad panels 2, 3 and, on the other hand, the flaps 13 and 14 extending from the narrow panels are correspondingly wider than the width of the comparatively narrow panels 4 and 5.

The blank 1 is then provided with a plurality of glue deposits 31, 32, 33 and 34. The glue deposit 31 extends parallel to and substantially along the longitudinal edge of the narrow side panel '5 and continues, in similar, striplike form, onto the adjacent flap 14 terminating just short of the lateral edge 20'. Deposit 32 on the flap 11 of the broad panel section 2 is substantially U-shaped with the legs of the U extending between and parallel to the slits 21 and 22 and the open end of said U-shaped configuration facing in the direction of the fold line 15 with the terminal portions thereof ending proximate to the fold line 15-. The deposits 33 and 34 on flap 12, which is contiguous to broad panel 3, are of similar configuration as the U-shaped deposit 32 except that the bottom of said U-shaped configuration is interrupted so that each of the deposits 33, 34- are spaced relative to and independent of each other; each of the major leg portions thereof extend to and between slits 23 and 24 and the contiguous portion adjacent to edge 20 is substantially at right angle to the leg portion and extends, in strip-like form, parallel to the edge 20 but slightly spaced with respect thereto. The glue deposit 31 serves for the formation of a longitudinal seam 35 after the blank 1 has been folded around a forming mandrel 29 and formed into a tube-like sleeve 30. This is accomplished by engaging, in a conventional manner, the strip-like deposit 31 with the overlapping seam portion 6.

The flaps 13 and 14- which are hingedly connected to the narrow panels 4 and 5, respectively, are then, by means of conventional tools-not shown, folded upon the face 36 of the forming mandrel 29 whereby the flaps 11 and 12 of the broad panels 2 and 3, respectively, come to rest approximately perpendicular to the side walls 2 and 3 of the sleeve 30. As a result the flap portions 25, 26, 27 and 28 of flaps 11 and 12, which enlarge. the transverse width of the narrow panel connected flaps 13 and 14, are thereby placed against the oppositely facing margins 11 and '12 as is illustrated in FIG. 1. After the flaps 13 and 14 of the narrow panels 4 and 5, respectively, have been folded as above described, a strip-like adhesive deposit 37 is laid transverse across the flaps 13 and 14 as is illustrated in FIG. 1. The strip 37 extends preferably, beyond the. flaps 13 and 14 and thus covers, as shown, partly portions of deposits 32, 33 and 34. In order that the adhesive deposit 37 may be applied without any difficulty, the flaps 11 and '12 of broad panels 2 and 3 respectively, and more particularly the surface opposite to that having gliue deposits 32, 33 and 34, are supported against movable plates 38 of forming mandrel 29.

I hereafter, the flap 12 is folded upon the flaps 13 and '14 of narrow panels 4 and respectively, in such a manner, that the area of the flap 12 between the adhesive deposits 33 and 34 come to rest upon the face 36 of the forming mandrel 29. The flap 11, which extends hingedly from broad panel 2, is then folded about the -flap 12, in an overlapping relationship and pressed thereagainst whereby the closure of the bottom is completed despite the gap between the edges of the flaps 13 and 14 as shown in FIG. 1.

Alternatively, the adhesive deposit 37 may, instead of being applied after the folding of flaps 13 and 14, as shown in FIG. 1, be placed upon the blank as is illustrated, in broken lines, in FIG. 2. This deposit, of course, takes place then upon the back surface of the blank 1. Suitably, in this case, heat responsive glue or adhesive material, such as dispersion adhesive, or melt adhesive is utilized which, after deposition upon the blank, dries immediately or solidifies and then during the fabrication of the bag closure is activated either through application of heat and/or pressure.

Finally, it should be noted that the bag closure in accordance with this invention is not limited exclusively to bottom closures but may also be used for forming top closures for bags.

What is claimed is:

1. In a bag of rectangular cross-section having a longitudinally extending body of alternating broad and narrow wall panels with a closure flap connected to each panel at one common end thereof; a longitudinally extending fold line between said panels and a transversely extending fold line between said closure flaps and said panels; the flaps adjoining the broad panels each having two slits extending from the outer edge of the flap in proximity to and parallel with said longitudinal fold line and terminating at a spaced distance from said transverse fold line, said distance being of sufiicient length to permit that during the folding of said narrow flaps which occurs prior to the folding of the main portion of the broad panels adjacent portions of said broad panels are folded therewith which, after folding, bear against other portions of the broad panel connected flaps; and adhesive means on each of said flaps, with the adhesive means on the flaps connected to the broad panels located on one side, and the adhesive means on the flaps connected to the narrow panels being located on the other side but in assembled position of the bag providing a contiguous adhesive region.

2. In a bag according to claim. 1, wherein in assembled condition the adhesive means on the broad panel connected flaps faces inwardly into the bag and the means on the narrow panel connected flaps faces in the opposite direction.

3. In a bag according to claim '1, wherein said adhesive means on each said narrow panel connected flaps is in strip-like substantially linear form.

4. In a bag according to claim 3, wherein said'means on each said broad panel connected flaps is angle shaped.

5-. In a bag according to claim 1, wherein the adhesive means on the narrow panel connected flaps extends beyond the marginal edges thereof for contact with the surface of the broad panel connected flaps.

6. In a bag according to claim 1, wherein said bag is formed from a one piece pre-cut blank and said adhesive means on the narrow panel connected flaps is secured prior to assembly to said blank.

7. In a bag according to claim 1, wherein said fold lines are grooved or scored prior to the assembly of said bag.

References Cited UNITED STATES PATENTS 1,029,783 6/ 1912 Appel 229-59 2,157,392 5/1939 Williams 229-- FOREIGN PATENTS 104,833 4/ 194-2 Sweden.

DAVID M. BOCKENEK, Primary Examiner U.S. Cl. X.R. 229-53, 59 

